Calreticulin-mediated protein folding in health and disease

健康和疾病中钙网蛋白介导的蛋白质折叠

• 批准号: 10362228
• 负责人: MALINI RAGHAVAN
• 金额: $ 45.81万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-03-10 至 2026-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10362228
• 关键词: Abnormal Cell; Address; Affect; Affinity; Alleles; Antigen Presentation; Antigen-Presenting Cells; Antigens; Apoptotic; Base Pairing; Binding; Binding Proteins; Binding Sites; Blood Platelets; Bone Marrow; Bone Marrow Cells; C-terminal; CD8-Positive T-Lymphocytes; CD8B1 gene; Calcium; Calcium Binding; Calcium Signaling; Cell Maturation; Cell Proliferation; Cell surface; Cells; Charge; Chronic; Complex; Dendritic Cells; Dependence; Disease; Disulfides; Endoplasmic Reticulum; Environment; Fibrosis; Frameshift Mutation; Genes; Glycoproteins; Growth Factor Receptors; Health; Hemorrhagic Thrombocythemia; Homeostasis; Human; Hyperplasia; Immune Evasion; Immune response; Immune system; Immunity; Immunologics; Immunotherapeutic agent; Impairment; Induced Mutation; Infection; Inflammation; Knowledge; Light; Link; MPL gene; Major Histocompatibility Complex; Malignant Neoplasms; Measures; Mediating; Mediator of activation protein; Megakaryocytes; Mission; Molecular; Molecular Chaperones; Mutagenesis; Mutate; Mutation; Myelofibrosis; Myeloproliferative disease; Nature; Oncogenic; Pathway interactions; Patients; Peptides; Phagocytosis; Phosphatidylserines; Primary Myelofibrosis; Process; Production; Proteins; Recurrence; Research; Sampling; Site; Somatic Mutation; Specificity; Splenomegaly; T cell response; United States National Institutes of Health; base; calreticulin; cell transformation; combat; dimer; disability; disulfide bond; driver mutation; human disease; insertion/deletion mutation; insight; leukemia; lysyl-aspartyl-glutamyl-leucine; monocyte; mutant; neoantigens; neoplasm immunotherapy; novel; peptide I; precursor cell; protein activation; protein folding; response; tool

Abstract Calreticulin (CRT) is a calcium-binding endoplasmic reticulum (ER) chaperone that is important for the folding of many N-linked glycoproteins. It is best known for its function in the assembly of major histocompatibility complex (MHC) class I (MHC-I) molecules, which present peptide antigens to CD8+ T cells for protective immunity against cancers and infections. Recent studies show that somatic frameshift mutations that alter the C-terminus of CRT are one class of driver mutations in myeloproliferative neoplasms (MPN). A 52 base-pair deletion mutant CRTDel52 and a 5 base-pair insertion mutant CRTIns5 are recurrent mutations in essential thrombocythemia (ET), primary myelofibrosis (PMF) and post-ET myelofibrosis (MF). It is our overall hypothesis that the changes to the sequence and charge of the C-terminal domains of CRT induced by the mutations enable both megakaryocyte transformation and immune system evasion in MPN. Although oncogenic transformation in megakaryocytes requires both mutated CRT and the thrombopoietin receptor/myeloproliferative leukemia protein (Mpl), the molecular mechanisms of mutant CRT-mediated constitutive activation of Mpl are unknown. CRT is known to be important for ER calcium storage and cellular calcium signaling, but precisely how MPN mutations alter these processes is not understood. The human MHC-I locus is highly polymorphic. While it is known that MPN-linked mutant CRTs are ineffectively incorporated into the MHC-I peptide-loading complex (PLC), it is unknown whether MPN CRT mutants have differential influences on the assembly of various MHC-I allotypes. Studies are proposed here to address these gaps in knowledge. We present evidence that disulfide-linked dimers of CRTDel52 are important for Mpl activation. The nature of CRTDel52 dimers and their complexes with Mpl will be elucidated using structural and mutagenesis studies. The effects of CRT deficiency, haploinsufficiency and mutation upon cellular calcium signaling will be examined. Based on the knowledge of variable dependencies on CRT for cell-surface expression of MHC-I allotypes, we will examine whether MPN CRT mutants impair MHC class I assembly for some allotypes, but alter assembly and peptide display for some other MHC-I allotypes. Such alterations could be exploited for immunotherapeutic targeting of MPN. Finally, mutant CRT expression is also detectable in blood monocytes of MPN patients, leading to predictions of alterations to antigen presenting cell (APC) calcium signaling and phagocytosis, which will be examined. Taken together, these studies will further our understanding of how mutations of a ubiquitous ER chaperone drive cell transformation, and influence the fundamental immunological processes of antigen presentation and phagocytosis.

抽象的 钙网蛋白（CRT）是钙结合内质网（ER）伴侣，对折叠很重要 在许多N连接的糖蛋白中。它以其在主要组织相容性的组装中的功能而闻名 复合物（MHC）I类（MHC-I）分子，将肽抗原呈现给CD8+ T细胞以进行保护 对癌症和感染的免疫力。最近的研究表明，会改变 CRT的C端是骨髓增生性肿瘤（MPN）中的一类驱动突变。 52个基础 删除突变体CRTDEL52和5个碱基对插入突变体Crtins5是必需的复发突变 血小板血症（ET），原发性骨髓纤维化（PMF）和ET骨髓纤维化（MF）。这是我们的整体 假设的变化是由CRT的C末端结构域的序列和电荷变化 突变使MPN中的巨核细胞转化和免疫系统逃避。虽然 巨核细胞中的致癌转化需要突变的CRT和血栓蛋白 受体/脊髓增生性白血病蛋白（MPL），突变体CRT介导的分子机制 MPL的组成型激活未知。 CRT对于ER钙存储和细胞很重要 钙信号传导，但尚不清楚MPN突变如何改变这些过程。人类 MHC-I基因座是高度多态性的。虽然已知MPN连接的突变体CRT无效 纳入MHC-I肽载体配合物（PLC），MPN CRT突变体是否具有 对各种MHC-I同种型组装的差异影响。这里提出了研究来解决这些 知识差距。我们提供了证据表明，CRTDEL52的二硫键连接二聚体对于MPL很重要 激活。 CRTDEL52二聚体及其与MPL的复合物的性质将使用结构和 诱变研究。 CRT缺乏症，单倍不足和突变对细胞钙的影响 信号将检查。基于对细胞表面CRT的可变依赖性的知识 MHC-I同型的表达，我们将检查MPN CRT突变体是否会损害MHC I类组装 某些同种型，但在其他一些MHC-I同种型中显示了更改组件和肽。这样的改变可能 被利用用于MPN的免疫治疗靶向。最后，在 MPN患者的血液单核细胞，导致抗原呈现细胞（APC）钙改变的预测 信号传导和吞噬作用将进行检查。综上所述，这些研究将进一步 了解无处不在的ER伴侣的突变如何驱动细胞转化，并影响 抗原表现和吞噬作用的基本免疫学过程。